Battery with strength indicator

ABSTRACT

A battery strength indicating and switch means on a battery which is coupled across the terminals of the battery and which is provided with an indicating means to indicate the strength of the battery and in addition, the battery strength indicating means is also provided with an in-line switch which can easily be depressed to complete the circuit so as to place the indicator means across the terminals of the cell and display the charge of the battery.

This is a continuation Ser. No. 07/816,144 filed on Dec. 31, 1991, nowU.S. Pat. No. 5,156,931.

FIELD OF THE INVENTION

The present invention relates to an improved battery having a built-instrength indicator device for determining the strength, voltage, orcapacity of the battery. More particularly, the present inventionrelates to a battery having an indicator cell which visually indicateswhen the battery is above or below a predetermined voltage value, an LEDarray which indicates when the battery is above or below a predeterminedvoltage value, or a redox cell which indicates when the voltage outputis above or below a predetermined voltage by a color change.

BACKGROUND OF THE INVENTION

Batteries are employed extensively in this country and abroad forautomobiles, home uses, industrial uses, recreational uses, and militaryuses. A battery is normally tested by measuring its voltage outputwithout a load. If the voltage is below a predetermined value, and thevoltage characteristics of the battery with respect to the battery'scapacity are known, one can determine whether the battery has sufficientcapacity to perform a desired function. A more accurate indication ofthe battery's condition can be determined by noting the voltage drop ofthe battery under a load. A well-charged battery will experience only aslight voltage drop under a load, whereas a depleted battery willundergo a significant voltage drop under a load. For a wet-cell battery,the work capacity of the battery can frequently be determined bymeasuring the specific density of the electrolyte.

A dry-cell battery does not have a reservoir liquid electrolyte; thus,its capacity cannot be determined by taking specific gravitymeasurements. In addition, voltmeters are expensive, as are devices formeasuring the voltage output of a battery, both under a load and underno load. Accordingly, most batteries are purchased or used without thepurchaser/user knowing the true condition of the battery.

Recently, the manufacturer of DURACELL-brand batteries has beendate-marking its packages to indicate by which date the battery shouldbe in use. Although this date-stamping may be of some benefit topurchasers, it does not tell the purchaser the actual condition of thebattery. Moreover, date-stamping of the package does not includedate-stamping of the battery; thus, the purchaser has no idea of theuse-date of a particular battery once it has been removed from thepackage.

Our related U.S. patent application identified above discloses aflashlight with a built-in battery tester having a voltmeter, ammeter,or visual-indicating chemical or LED cell to indicate when the battery'svoltage output is above or below a predetermined value.

Flashlights, portable lanterns, portable radios and television, cameras,video recorders, portable dictating machine, and the like are usedextensively in this country and abroad. Almost every home and businesshas at least one flashlight or portable lantern and a radio. Many homeand businesses have numerous devices, such as recorders, portable radiosand televisions, video recorders, calculators, cameras, and the like,which utilize batteries for their energy source. Some of the devices,such as flashlights, are used on an infrequent basis, that is, during anemergency situation where there has been a power failure or when it isnot convenient to use a light source powered by conventional householdcurrent, such as for outdoor use or use in an unlighted attic or crawlspace. Other devices, such as portable radios, are used extensively. Themajority of these battery powered devices use dry-cell nonrechargeablebatteries. Nonrechargeable alkaline batteries sold under the trademarksEVEREADY, DURACELL, RAY-OVAC, and the like, have a number of advantagesover rechargeable batteries. On a weight-to-weight and volume-to-volumebasis, the alkaline battery can supply three to four times the wattageof a rechargeable battery. In addition, nonrechargeable dry-cellrechargeable batteries put out a higher voltage than dry-cellrechargeable batteries. Many dry-cell rechargeable batteries, even ifnot in use, have to be periodically charged to keep the batteries fromfalling below a defined charge level to prevent permanent damage to thebatteries. Alkaline batteries, which are used frequently, can have ashelf or storage life of from three to five years. During this period,no maintenance of the battery is required. In contrast, mostrechargeable batteries wet-cell and dry-cell will completely dischargewithin six months or less of their last recharge.

Most individuals test their batteries by turning on the device in whichthe batteries are installed. If the device operates, the individual isnormally satisfied that the batteries are operational. Some individualswill test the batteries on a battery tester to determine the conditionof the batteries. Some individuals will even test the batteries underboth loaded and unloaded conditions to measure the voltage drop.Although it is not complicated to test batteries, it is time consumingto disassemble a device, remove the batteries, test the batteries, and,if they pass the test, reinstall the batteries in the device. It isnormally not possible to test new batteries at the time of purchasebecause of the battery protective packaging.

Accordingly, it is the object of the present invention to provide animproved battery having a built-in battery-strength indicator whichpermits one to immediately determine the battery's strength orcondition. Thus, with the improved battery of the present invention, auser can quickly and effortlessly determine the strength or condition ofa battery. When a batter is easily tested, as the battery of the presentinvention, the user of the battery is more likely to routinely check thecondition of the battery.

SUMMARY OF THE INVENTION

The present invention is directed to an improved battery comprising abattery and a battery-strength indicator means to indicate the strengthof the battery when electrically connected to the battery. Optionally,the battery will include a switch means adapted in an “on” position toelectrically connect and complete a circuit between the battery and theindicator means.

In a preferred embodiment shown further herein, the improved batteryhaving a battery strength indicator comprises a dry cell battery havinga first terminal and a second terminal; a battery indicator formed in alayer attached to a side of the battery which undergoes a visible changewhen subject to a predetermined voltage potential and a first conductorelectrically connected between one end of the indicator and the firstbattery terminal; and a battery switch comprising a resilient,nonconductive, deformable layer disposed over the side of the battery, aswitch chamber formed beneath the resilient layer, and a secondconductor extending from the chamber and connected to the other end ofthe indicator, the portion of the second conductive lead within theswitch chamber comprising a switch contact, the battery switch beingbiased in an electrically open position. Upon pressing of the resilientlayer over the switch chamber, the switch contact will be placed inelectrical contact with a conductive layer in electrical contact withthe second battery terminal, thereby placing the indicator in electricalcontact across the terminals of the battery to quickly indicate to theuser the strength of the battery.

In another preferred embodiment shown herein, the improved batteryhaving a battery strength indicator comprises a dry cell battery havinga first terminal and a second terminal; a battery indicator attached toa side of the battery which undergoes a visible change when subject to avoltage potential which exceeds or drops below a predetermined value anda first conductor electrically connected between one end of theindicator and the first battery terminal; and a battery switchcomprising a resilient, nonconductive, deformable layer disposed overthe side of the battery, a switch chamber formed beneath the resilientlayer, a second conductor extending from one end of the chamber andconnected to the other end of the indicator, and a third conductorextending from the other end of the chamber to the second batteryterminal, the battery switch being biased in an electrically openposition. Upon pressing of the resilient layer over the switch chamber,the switch places the indicator in electrical contact across theterminals of the battery to quickly indicate to the user the strength ofthe battery.

In yet another embodiment, the invention is directed to a strip or labelfor application to a battery which includes an integral battery-strengthindicator or voltmeter which comprises a first nonconductive insulatingor dielectric base layer and a conductive layer above and in contactwith the base layer. A nonconductive insulating or dielectric layer maybe provided over and in contact with the conductive layer. A heat ortemperature sensitive, color indicating layer thermally contacts theconductive layer. The conductive layer has sufficient heat generatingcapacity when subject to a predetermined voltage to cause a color changein the temperature sensitive, color indicating layer. The conductivelayer is preferably formed with a reduced cross sectional area to have aresistance such that current flow at a minimum predetermined voltagethrough the conductive layer will raise the area to a predeterminedtemperature. The base layer is of sufficient thickness to providethermal insulation to overcome heat sinking under the conductive layerand permit the temperature sensitive, color indicating layer to functionwhen the strip containing the battery strength indicator or voltmeter isapplied to the side or housing of a battery, which battery typically hasan electrically conductive housing. The strip comprising thebattery-strength indicator or voltmeter also includes switch meansadapted to make electrical contact with a terminal of the battery, whichterminal may comprise the electrically conductive battery housing.

The battery-strength indicator means can comprise a nonconductive baselayer; a nonconductive top layer attached to the base layer, a portionof the top layer and base layer forming a chamber therebetween; firstand second conductive means separately and independently positionedbetween the top layer and the base layer and extending into the chamber,the ends of the conductive means in the sealed chamber formingelectrodes, the other ends of the conductive means adapted toelectrically connect to the battery; and indicator means in the sealedchamber adapted to undergo a visible change when the voltage potentialacross the electrode exceed or crosses a predetermined voltage. Theindicator means can be a liquid-crystal composition that changes phaseswhen the field between the electrodes or plates exceeds or crosses apredetermined voltage value. Preferably the chamber is sealed.

In an alternative embodiment of the present invention, the batterystrength indicator means comprises a first nonconductive layer; a secondnonconductive layer attached to the first layer, a portion of the firstand second layers forming a chamber therebetween, the chamber havingfirst and second internal opposing walls; a third nonconductive layerhaving a high dielectric constant attached to the first internal wall ofthe chamber; a first conductive plate means sandwiched between the thirdinsulating layer and the first internal wall and isolated from thechamber; a second conductive plate means on the second internal wall;first and second conductive means separately and independentlypositioned between the first and second nonconductive layer, the ends ofthe conductive means electrically connected to the first and secondconductive plate means respectively, the other ends of the conductivemeans adapted to be electrically connected to the battery; and aliquid-crystal composition in the sealed chamber adapted to undergo avisible phase change when the electric field between the first andsecond plate means “exceeds or crosses a predetermined value. Preferablythe chamber is sealed.

One embodiment of the switch means of the present invention comprises anonconductive base layer; a resilient nonconductive top layer attachedto the base layer, a portion of the top and base layers forming achamber having first and second internal spaced apart opposing wells; afirst contact means on the first internal wall of the chamber; a secondcontact means on the second internal wall of the chamber; first andsecond conductive layers independently and separately sandwiched betweenthe top layer and the base layer and connected to the first and secondplate means respectively, the top layer about the chamber adapted to bepushed toward the base layer so that the first and second contact meanscome in contact to permit current to flow from the first conductivemeans to the second conductive means.

In an alternative embodiment of the switch means of the presentinvention, the switch means comprises a nonconductive base layer; aresilient nonconductive top layer attached to the base layer, a portionof the top and base layers forming a chamber having first and secondinternal spaced apart opposing walls; first and second spaced apartconductive contact means on the first internal wall of the switchchamber; third conductive contact means on the second internal wall ofthe chamber; and first and second conductive means independently andseparately sandwiched between the top layer and base layer and connectedto the first and second conductive contact means respectively, the toplayer about the chamber adapted to be pushed toward the base layer sothat the third conductive contact means contacts the first and secondconductive contact means to complete an electrical connection with thefirst and second conductive contact means.

In another embodiment of the present invention, the battery-strengthindicator means comprises a first nonconductive layer; a secondnonconductive layer attached to the first nonconductive layer, a portionof the first and second nonconductive layers forming a chambertherebetween; a conductive layer sandwiched between the first and secondnonconductive layers, the conductive layer reduced to a smallcross-sectional area in the chamber; and a heat sensitivecolor-indicating material in the sealed chamber that is adapted toundergo a color change when its temperature exceeds or crosses apredetermined value, the conductive layer in chamber rising to apredetermined temperature when the voltage of the current flowingtherethrough exceeds a predetermined value.

In a further embodiment of the present invention, the battery-strengthindicator means comprises a first nonconductive layer; a secondnonconductive layer attached to the first nonconductive layer, a portionof the first and second nonconductive layers forming a chambertherebetween; a conductive layer sandwiched between the first and secondnonconductive layers, the conductive layer reduced to a small crosssectional area in the chamber; a pyrotechnic material contained withinthe chamber and adapted to decompose when the temperature of the firstsection of the conductive layer in the chamber exceeds a predeterminedtemperature, the first section of the conductive layer adapted to exceedthe predetermined temperature when the voltage of the current throughthe conductive layer in the chamber exceeds a predetermined value.

In a further embodiment of the present invention, the battery-strengthindicator means comprises a first nonconductive layer; a secondnonconductive layer attached to the first nonconductive layer, a portionof the first and second nonconductive layers forming a chambertherebetween; and a conductive layer sandwiched between the first andsecond nonconductive layers, the conductive layer reduced to a smallcross sectional area in the chamber such that when the voltage ofcurrent flow through the conductive layer in the chamber exceeds apredetermined value, the temperature of the conductive layer in thechamber exceeds the melting temperature of the conductive layer causingthe conductive layer to melt and form an open circuit.

The invention also comprises an improved battery package having abattery-strength indicator means comprising at least one battery; abattery-strength indicator means comprising a battery-strength indicatordevice for indicating the strength of the battery when electricallyconnected to the battery; and conductive means adapted to electricallyconnect the indicator device to the battery; and packaging means for thebattery and battery-strength indicator means.

The deformable, nonconductive strip layer or layers employed inconnection with the battery strength indicator and switch may be made ofplastic film such as adhesive tape for application to the batteryhousing or battery packaging. Preferably the chambers of the batterystrength indicators are sealed chambers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a battery-strength indicator device of thepresent invention;

FIG. 1A is a top view of a battery-strength indicator device of thepresent invention with a switch;

FIG. 2 is a perspective view of a battery of the present inventionhaving a battery-strength indicator device;

FIG. 3 is a vertical, sectional view along lines 3—3 of FIG. 1;

FIG. 4 is a top plan view of a battery-strength indicator device of thepresent invention;

FIG. 5 is a vertical, sectional view along line 5—5 of FIG. 4;

FIG. 6 is a vertical, sectional view of a switch of the presentinvention with the switch in the “off” position;

FIG. 7 is a vertical, sectional view . . . of a switch of the presentinvention with the switch in the “on” position;

FIG. 8 is a vertical, sectional view of an alternative switch of thepresent invention;

FIG. 9 is a vertical, sectional view of an alternative embodiment of thebattery-strength indicator device of the present invention;

FIG. 10 is a top plan view of another alternative embodiment of thebattery-strength indicator device of the present invention;

FIG. 11 shows a top plan view of still a further embodiment of thebattery-strength indicator device of the present invention;

FIG. 12 is a perspective view of the battery packaging of the presentinvention having a battery-strength indicator device;

FIG. 13 is a schematic diagram of the battery packaging circuitry of thepresent invention having a battery-strength indicator device;

FIG. 14 is a vertical, sectional view of an alternative embodiment ofthe switch of the present invention;

FIG. 15 is a vertical, sectional view of another embodiment of thebattery-strength indicator device of the present invention; and

FIG. 16 is an enlarged, sectional view within encircled line 16 of FIG.15.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a battery-strength indicator device 10 of thepresent invention is illustrated. The indicator device has an indicatorchamber, cell or bubble 12 formed in strip 16. Preferably the cells ofthe present invention are sealed cells. Conductive layers 14 run thelength of the strip into the indicator bubble to form spaced apartelectrodes. The indicator bubble contains an indicating material 17which undergoes a visible change when the voltage potential across theindicator cell exceeds a predetermined value. At least one side of thestrip 16 is transparent or translucent.

The improved battery 18 of the present invention is illustrated in FIG.2. The battery has an anode 20 and a cathode at its base (not shown).The indicator device 10 is attached to the side of the battery, with theends of the device connected to the anode 20 and the cathode. If thedevice is a constant-drain device, that is, the device is oncontinuously, the indicator cell undergoes a visible change when theoutput voltage of the battery drops below a predetermined value. In analternative embodiment of the invention, the battery has the indicatordevice of FIG. 1A, which includes a strip 16, conductive leads 14, anindicator cell 12, and a switch 24. The switch is biased to be in an“off” position, and, thus, the indicator device is only actuated whenthe switch is “on”, thus preventing a constant drain on the battery.

Referring to FIG. 3, the indicator device 10A comprises a first layer30, a second layer 32, and a conductive layer or lead 14 sandwichedbetween the first and second layers. The end of the conductive leadsextend into the indicator chamber or cell 12, which is filled with anindicator material 33. The ends of the conductive leads form electrodes36. The second layer of the device of FIG. 3 is formed with the bulge 37which forms one side of the cell. The other side of the cell is formedby the first layer. The first layer can be a clear material, atranslucent material, or an opaque material. The second layer ispreferably a clear or translucent material. The first layer can be anopaque material as long as the bulge area is clear or translucent. Ifthe first layer is opaque, the inner side 31 of the first layer can becoated with a reflective material such as aluminum or aluminum foil, ora highly reflective white material to enhance-visibility of theindicator material.

The indicator material can be any material that will undergo a visiblechange, such as a color change, when the voltage potential across theelectrodes exceeds or drops below a predetermined voltage. For example,the material can be a redox composition, such as the composition in theU.S. Sterling U.S. Pat. No. 1,497,388, or the compositions disclosed byH. A. Fales and F. Kenny, INORGANIC QUANTITATIVE ANALYSIS, 1939, pp.391–393, or the like. Alternatively, the composition can be aliquid-crystal composition, such as one of the compositions disclosed inKirk-Othmer, ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, 3rd Ed., John Wiley &Sons, Vol. 7, pp. 724–751 and Vol. 14, pp. 395–427.

The voltage color-indicating device of the present invention comprises asealed cell having at least one transparent or translucent window. Thecell is filled with an aqueous or non-aqueous composition, such as anaqueous phenophthalein solution. Two spaced-apart electrodes of the cellare in contact with the color-indicating solution. When a voltagepotential is induced across the electrodes, a redox reaction occurswhich can cause a color change in the color-indicating solution. Eachsolution has its own unique threshold voltage wherein the redox reactionwill commence. If the voltage of the battery is below that thresholdvoltage, no redox reaction will occur and there will be no color change.

An alternative embodiment of the battery-strength indicator device 10Bof the present invention is illustrated in FIGS. 4 and 5. The indicatordevice 10B has a first layer 30, and a second layer 32 a, and conductiveleads or layers 14 sandwiched therebetween. The second layer 32 a has adepression or cavity 38 which defines one side of the indicator cell 12;the other side of the cell being defined by the inner surface 31 of thefirst layer 30. The cavity is illustrated with curved surfaces, it canalso have straight sides arranged in perpendicular or nonperpendicularfashion. One or both of the layers are transparent or translucent.Although the drawing illustrates the layers as being relatively thick,in actual practice the layers can be quite thin, such as 1 or 2 mils,with the cell having a maximum height or depth of 0.5 or 1 mil.

One embodiment of the switch 44 of the present invention is illustratedin FIGS. 6 and 7. The switch 44 has a base layer 46 and a resilient toplayer 48, which is attached to the base layer. Conductive leads orlayers 50 a and 50 b are sandwiched between the two layers. Theconductive layer 50 a on the left side of the device is separated fromthe conductive layer 50 b on the right side of the device by spacing 51.A portion of the top layer is bulged out to form a bubble element 56. Aconductive strip or coating 54 is attached to the inner side 55 of thebubble element. The bubble element is biased away from the base layer 46as shown in FIG. 6 so that the conductive strip or coating does not comein contact with the switch contacts 52. Thus, the switch is normally inthe “off” position. When the bubble element is pressed downwardlytowards the base layer as shown in FIG. 7, the conductive strip 54contacts the switch contacts 52; thus bridging the contacts andpermitting current flow across the contacts between the conductive leadsor layers 50 a and 50 b, as illustrated in FIG. 7. When pressure isremoved from the bubble element, the bubble element biases away from thebase layer, breaking contact between the two contacts 52.

An alternative embodiment of the switch 44A of the present invention isillustrated in FIG. 8. This switch has a base layer 46, a resilient toplayer 48, and conductive leads or layers 50 sandwiched between the twolayers. The top layer is bulged out to form a bubble element 56. Theswitch contacts 52 are located on the inner sides of the bubble element.A conductive strip 54 or coating is attached to the inner side of thebase layer 46. This switch operates in the same manner as does theswitch of FIGS. 6 and 7. The bubble element is depressed to have theswitch contacts 52 make contact with the conductive strip 54; thus,electrically bridging the two contacts. The bubble element is biasedaway from the top layer so that the switch is normally in an “of f”position. When pressure is removed from the bubble element, the bubbleelement biases away from the conductive strip; thus, breaking contactbetween the switch contacts and the conductive strip.

Another embodiment of the battery-strength indicator device of thepresent invention is illustrated in FIG. 9. The device loc has a firstlayer 30 and a second layer 32. Conductive layers 14 a and 14 b areindependently and separately sandwiched between the first and secondlayers on the left and right sides respectively of the device. A portionof the first layer is formed into a bulge 37 to form the indicator cell12. A plate or electrode 60 a is attached to the inner surface 31 of thetop layer within the cell and is electrically connected with conductivelayer 14 a. A second plate or electrode 60 b is attached to the innerside 35 of the second layer 32 within the indicator cell and iselectrically connected to the conductive layer 14 b. The indicator cellis filled with an indicator material 17, such as the material describedabove. At least one of the layers and its attached plate are transparentor translucent (or one of the layers is transparent or translucent andits attached plate is extremely thin) so that changes to the indicatormaterial are visible.

The basic architecture of the indicator device of FIG. 9 can also beutilized for another embodiment of the switch of the present invention.When the architecture Is employed as a switch, the bulge 37 is biasedaway from the second layer 32, and the indicator cell is not filled withan indicator material. Two switch contacts replace the electrodes 60 aand 60 b and the switch operates when the bulge is depressed downwardlyto make contact between the switch contact attached to the inner side ofthe first layer and the switch contact mounted on the inner side of thesecond layer.

Another embodiment of the battery-strength indicator device of thepresent invention is shown in FIG. 10. The indicator device 10D is astrip like device having first and second superimposed layers 30 and 32which are attached together in the same manner as strips 30 and 32 inFIG. 3. At least one of the strips is transparent. Conductive layers 64are sandwiched between the first and second layers. The conductive layeris reduced to a small cross-section 65 in the indicator zone 66. Withinthe indicator zone, the conductive layer is covered with a small amountof a pyrotechnic chemical 68 sensitive to heat. Surrounding thepyrotechnic chemical is a color indicating, heat-sensitive material 70which will undergo a visible color change, either permanent ortemporary, when the material is heated to at least a predeterminedtemperature. This battery-strength indicator device is a one-shotdevice; the pyrotechnic chemical will only decompose or react once. Thepyrotechnic chemical undergoes rapid decomposition when it is heated toa predetermined temperature. The resistance of the conductive layer inthe reduced cross-sectional area 65 is selected such that current flowat a minimum predetermined voltage through the conductive layer willraise the area to a predetermined temperature which will cause thepyrotechnic chemical to decompose or otherwise react. The pyrotechnicchemical in turn will raise the temperature of the color-indicating,heat sensitive material to the predetermined temperature for colorchange.

Although the indicator device of FIG. 10D is shown with acolor-indicating, heat-sensitive material, the device can also befabricated with the pyrotechnic chemical alone, thereby causing a slightcharring to the strip which is noticeable. One of the strips can also bemade of a material that is sensitive to temperature and will undergo avisible change when the temperature exceeds a predetermined value.Alternatively, the device can be fabricated without the pyrotechnicchemical, relying on the color-indicating, heat-sensitive material aloneto indicate whether the battery has a predetermined minimal voltageoutput. If the color indicating, heat-sensitive material undergoes anon-permanent color change when exposed to a predetermined temperature,then the battery-strength indicator device of FIG. 10D can be usedrepeatedly to determine if the output voltage of the battery meets apredetermined voltage level.

A further embodiment of the battery-strength indicator device of thepresent invention is illustrated in FIG. 11. The battery-strengthindicator device 10E has first and second layers 30 and 32 which aresandwiched together like layers 30 and 32 in FIG. 3. The conductivelayers 64 are sandwiched between the first and second layers. Theconductive layer is reduced to a small cross-section area 75 within theindicator cell 66. The resistance of the conductive layer and thecross-sectional area 75 are selected such that the current flow of apredetermined minimum voltage potential through the conductive layerwill melt the area 75 in the fashion of a fuse element, causingconductive strip in area 75 to become an open circuit. The vaporizationof the melted conductive strip forms a visible sign that the area 75 washeated to a predetermined temperature which can only be achieved whenthe device is subject to a predetermined minimum voltage.

Another embodiment of the invention is shown in FIGS. 12 and 13. Abattery package 84 comprises two batteries 18 mounted on a package frame82. Conductive leads 14 a and 14 b are affixed to the base of the framein electrical contact with the cathode 22 of the battery. A conductivelead 14 connects the leads 14 a and 14 b with a batterystrength-indicator 10, such as the ones described herein. A conductivelayer 50 connects the indicator 10 with the switch 44 which in turn isconnected to a conductive T-connection 86. The T-connection iselectrically connected to the battery anodes 20 via conductive layer 50and conductive flaps 86. The package is intended to be covered with atransparent cover giving physical access to the switch 44 and visualaccess to the indicator 10. In the embodiment of FIG. 12 the batteriesare in parallel. FIG. 13 illustrates the circuitry of a battery packagecontaining two batteries that are connected in series to the switch 44and indicator 10.

In the preferred embodiment of the conductive leads, switch andindicator are layers attached to the package frame. The conductive leadsmay be printed or silk screened directly on the package frame. Thepackage frame can be the base nonconductive layer for the switch 44 andindicator 10.

Another embodiment of the switch 44 of the present invention isillustrated in FIG. 14. The switch has a base layer 46 and a top layer48, which is attached to the base layer. Conductive leads or layers 50 aand 50 b are sandwiched between the two layers. The conductive layer 50a on the left side of the device is formed into switch contact 62 a inchamber 40 and the conductive layer 50 b on the right side of the deviceis formed into switch contact 52 b in the chamber. A portion of the toplayer and bottom layer are bulged out to form bubble elements 56 a and56 b. The bubble elements are biased away from each other so that theswitch contacts do not come in contact. Thus, the switch is normally inthe “off” position. When the bubble elements are pressed together asshown by the arrows in FIG. 14, the switch contacts come in contactpermitting current flow across the contacts and the conductive leads orlayers 50 a and 50 b. When pressure is removed from the bubble elements,the bubble elements bias away from each other, breaking contact betweenthe two switch contacts.

The present invention permits the user of a batter to quickly determinewhether the capacity of the battery is above or below a given pointwithout the use of a voltmeter and/or ammeter. The approximate capacityof a battery can be determined by the battery's no load output voltage.The indicator device of the present invention can be fabricated so thatit indicates a particular no-load voltage threshold. For example, onecan select a voltage threshold which is indicative that the battery isabout 20% exhausted, or about 50% exhausted—whatever is suitable for theintended purpose.

The indicator having a liquid-crystal composition comprises a sealed,fully-enclosed cell containing the liquid-crystal composition.Preferably, one side of the cell will be transparent, and not merelytranslucent. The base layer of the liquid-crystal indicator call can bea high-dielectric material, optionally coated with a dielectric mirrorin contact with the liquid-crystal composition. The top layer ispreferably transparent and, optionally, has a transparent, conductivecoating applied to the surface in contact with the liquid-crystalcomposition. A voltage differential is induced across the liquid-crystalcomposition to either the base high-dielectric material or thehigh-dielectric transparent top layer to induce electric field. Anelectric field change can cause changes in the optical properties ofliquid crystals, such as when a liquid crystal changes from a nematicphase to a smectic phase. Such field are easily achieved, even withsmall voltage inputs from batteries, by employing a high-dielectric basematerial and/or a high dielectric top layer material. Thus, when theliquid-crystal detector of the present invention is in a non-energizedstate, it will have one optical appearance characteristic of the ‘atrest’ phase of the liquid crystal. When the indicator device isactivated, and a field is generated across the liquid-crystalcomposition, the liquid-crystal composition will transform into anotherphase. Alternatively, the indicator can remain in an “always on”condition and provide a constant indication of battery strength. Ifbatteries do not have sufficient voltage to achieve the thresholdhigh-dielectric field, thereby changing the liquid-crystal compositionfrom one phase to the other, no change will be observed. Thus, eachliquid-crystal indicator cell will be tailored by controlling thethickness of the dielectric material in the sandwich, the distancebetween the plates or electrodes, and the dielectric composition.Typical liquid-crystal compositions that can be employed includemethoxybenzylidenebutylaniline and terephthal-bis-p-butyl-aniline.

In the indicator device of FIG. 15, the electrodes 62 b and 62 a areindependently and separately sandwiched between the first highdielectric constant layer and the third nonconductive layer 30 and 34and the first layer and second nonconductive layers 30 and 32,respectively. A bulge extending outwardly from the he first layer isformed in the second layer to form an indicator cell 40. Within the cellon the inner side of the second layer 32 and a plate 62 a is attached orcoated and electrically connected to lead 14 b. Plate 62 b is positionedbelow the indicator cell between the first and third layers and iselectrically connected to conductive layer 14 a. The indicator cell 12is filled with a liquid-crystal composition 40. The second layer andplate 62 a and/or the first and third layers and plate 62 b aretransparent or translucent so that changes to the liquid-crystalcomposition 40 are visible. The bottom of the chamber can include ahighly reflective coating or the like to enhance observation of the”changes to composition 40. The arrangement of the first, second, andthird layers of the conductive layer 14 a is shown in the enlarged,sectional view of FIG. 16.

Other constructions of the battery strength indicators and switches arecontemplated within the scope of this invention. For example, anindicator can be fabricated with conductive top and base layers whichsandwich a nonconductive layer. A cell is formed between the top andbottom layers as described herein. The nonconductive layer does notextend into the cell; this layer, however, does electrically insulatethe top layer from the bottom layer. The cell is filled with anindicator material as described herein and the top and bottom layer areindependently adopted to be connected to different poles of a battery.The top and/or bottom layer are transparent or translucent.

Another indicator embodiment contemplated by the present invention issimilar to indicator 10D of FIG. 10. This alternative embodiment has topand base layers sandwiching a conductive layer that is reduced to asmall cross-sectional area in a indicator region of the indicator. Thetop layer and/or base layer undergo color changes when the temperaturecrosses a predetermined threshold. The conductive layer in the indicatorregion is adopted to exceed the predetermined temperature threshold whenthe voltage potential across the conductive layer exceeds apredetermined voltage.

In another embodiment of the indicator, the indicator can use a BIOMETALmaterial of TOKI AMERICAN TECHNOLOGIES, INC. of Irvine, Calif. BIOMETALmaterial is a shape memory alloy which changes its internal structure ata predetermined temperature and takes on an entirely new space. ABIOMETAL material can be used in place of the pyrotechnic material orcolor indicating material of the device 10D of FIG. 10 to indicatewhether the battery has a predetermined voltage.

The present intention can be used with a dry cell battery or with awet-cell battery and with both rechargeable and nonrechargeablebatteries. However, for purposes of convenience, the invention has beendescribed herein with respect to a dry-cell battery.

The modern nonrechargeable alkaline dry-cell battery has a decliningoutput voltage over its useful life. A new battery has an output voltageof about 1.60 volts. After one hour of continuous use, a battery'svoltage output (no-load) drop to between 1.40 volts and 1.45 volts.Thereafter, for the majority of the battery's useful life, the battery'sno-load voltage gradually decreases in a somewhat linear fashion. As abattery approaches the end of its useful life, the no-load voltage dropsto about 1.0 volt. However, the battery still has some capacity and canbe marginally used in this weakened condition for very brief periods oftime. When the battery's voltage drops below 1.0 volt, the battery isnear the end of its life, and the remaining capacity of the battery isvery limited. Near the point of exhaustion, the battery's output voltagerapidly drops from about 1.0 volt to about 0.5 or 0.6 volt.

The light-output candle-power of a portable lantern or flashlight bulbis somewhat sensitive to the battery voltage. Incandescent lamps aredesigned to operate optimally at a specific voltage. If the voltage isappreciably exceeded (such as by 50%) for any period of time, the filmof the lamp will rapidly melt or vaporize, destroying the lamp. Mostlamps are designed for voltages in increments of 1.2 volts. Thus,portable-lantern incandescent lamps are designed optimally for an outputvoltage of about 4.8 volts (a 6-volt lantern), and single-cell,double-cell, triple-cell, four-cell, and five-cell flashlightincandescent lamp are designed for an output voltage of 1.2, 2.4, 3.6,4.8, and 6.0 volts respectively. However, flashlight and lantern bulbswill operate effectively over a broad range. For example, a two-celllantern bulb or lamp will operate effectively from about 3.2 volts toabout 2.0 volts. However, when the voltage of each battery drops below1.0 volt, the output of the incandescent lamp is noticeably affected,and the color of the emitted light shifts from a yellow-white light to ayellow-red light.

Three sets of batteries were tested in three identical flashlights, withthe batteries being switched between the flashlights on a routine basis.The results of the tests are shown in the following tables. (The Romannumerals I, II, and III indicate the flashlight, and the numbers, 1A,1B, 2A, 2B, 3A and 3B indicate the individual batteries.) The first setof batteries (1A and 1B) were ENERGIZER brand alkaline batteries; thesecond set (2A and 2B) were DURACELL brand alkaline batteries, and thethird set (3A and 3B) were EVEREADY brand zinc-carbon batteries. Thebatteries were “D” size batteries. Battery 2A failed after 32 hours andwas replaced with a 3-year old DURACELL alkaline battery having ano-load voltage of 0.99 volt.

The flashlights were two-cell flashlights having incandescent lamps. Theincandescent lamps were rated at 1.2 volts and 0.5 amp. Thecold-filament internal resistance of the incandescent lamps was about0.4 amp. The hot-filament internal resistance of the incandescent lampswas not measured.

Each flashlight was loaded with a set of batteries and turned on. Fromtime to time, the flashlights were turned off and the no-load outputvoltage of the batteries was measured. On a periodic basis, the outputvoltage of the batteries under load was also measured. The tests werenot run on a continuous, 24-hour basis, but were run for periods ofapproximately 12 hours during the first two days, about 3 hours thethird day, about 7 hours during the fourth day, about 6 hours the ninthday, and 20 minutes the tenth day. No tests were conducted during thefifth, sixth, seventh and eighth days. The results show that the usefullife of a battery is near exhaustion when the voltage of the battery hasfallen below 1.0 volt. After the voltage of the battery drops below 1.0,the discharge rate of the battery (indicated by the voltage drop) canexceed 0.5 volt in a half-hour.

It appears, from the tables, that the useful life of the 1A and 1Bbatteries is about 28 to 29 hours and the half-life is about 14 hourswhere the output voltage is about 1.2 volts. When the output voltage ofthe batteries is about 1.3 volts, the batteries have about 75% of theiroperating life remaining. When the voltage of the batteries is about 1.1volts, the batteries have about 25% of their useful life remaining.

The 2A and 2B batteries appear to have a useful life of about 23 hoursand a half-life of about 12 hours where the output voltage is about 1.2.When the output voltage of the batteries is about 1.3 volts, thebatteries have about 75% of their useful life remaining. When the outputvoltage drops to about 1.15 volts, the batteries have only about 25% oftheir remaining useful life.

Batteries 3A and 3B, which are zinc-carbon batteries (LeChanche cell),had a much shorter life span than the alkaline batteries. Thesebatteries had a useful life of about 7.5 hours, with a half-life ofabout 3.5 to about 4 hours where the output voltage is abut 1.2 volts.When the batteries' output voltage is about 1.3 volts, the batterieshave about 75% of their remaining useful life. When the batteries'output voltage drops to about 1.1 volts, the batteries only have about25% of their useful life remaining.

When the no-load output voltage of the batteries dropped below 1.0 volt,all the batteries exhibited rapid voltage drops. When the batteriesreached the end of their useful life, the flashlights were turned offand the batteries were allowed to rest. Surprisingly, the batteries'output voltage would rebound and the batteries could be operated forbrief periods. As this cycle of rest and use was continued, thebatteries' ability to rebound decreased and the batteries experiencedmuch more rapid voltage drops under the load.

The tests indicate that, when the batteries are fresh, the total voltagedrop of a pair of batteries in series is somewhere from about 0.45 toabout 0.65 volt; that is, the total output voltage of the two batteriesin the flashlight under no-load will be about 3 volts, and under theload will be about 2.5 volts. As the batteries approached theirhalf-life, the voltage drops for the two batteries increased to about0.75-about 0.95 volt. When the batteries approached the end of theiruseful life, the voltage drop was in excess of 1.0 volt; that is, theoutput voltage of the two batteries under no-load was from about 2.0 toabout 2.2, and the voltage drop was from about 1.0 volt to about 1.7volts.

The tests also show that, when batteries have reached their exhaustionpoint but are allowed to rest for a few hours, their no-load outputvoltage will exceed 1.0 volt. However, when the batteries are then putunder a load, the working voltage of the batteries rapidly drops to aslow as 0.6 volt. This voltage drop can be observed because the outputvoltage of the batteries in the weakened condition does not drop in asingle-step manner but continues to drop over time, sometimes taking aslong as 30 seconds to stabilize. For example, two used DURACELL brandalkaline batteries, each having a no load output voltage of about 0.95volt, were placed (i.e., used) in a flashlight for one hour. At the endof one hour, the no-load output voltage of the batteries was about 0.45and 0.5 volt, respectively. The batteries were put under a load, and thevoltage immediately dropped between 0.6 and 0.7 volt, for both batteriesin series, and then continued to drop, over a 30 second period, for afinal value, for both batteries in a series, of 0.48 volt. This sametype of phenomenon was observed with the ENERGIZER alkaline batteriesand with the EVERREADY brand zinc-carbon batteries. Thus, the deviceequipped with exhausted batteries may give a strong operation for ashort period of time, but then will quickly decrease in power under theon-going load.

TABLE I BATTERY OUTPUT VOLTAGE IN OPERATION (Incandescent FlashlightBulb) Time Battery Voltage (Hours) 1A 1B 2A 2B 3A 3B 0.00 1.60 1.60 1.591.60 1.60 1.60 1.00 1.45 1.45 1.45 1.45 1.35 1.35 1.50 1.40 1.45 1.401.40 1.30 1.30 2.00 1.40 1.40 1.35 1.35 1.30 1.30 2.50 1.39 1.39 1.351.35 1.30 1.30 3.50 1.39 1.39 1.32 1.32 1.20 1.20 4.50 1.39 1.39 1.301.30 1.20 1.19 5.50 1.30 1.30 1.30 1.30 1.10 1.10 6.50 1.30 1.30 1.301.30 1.05 1.02 7.50 1.30 1.30 1.29 1.29 1.01 1.01 10.00 1.29 1.29 1.281.25 0.89 0.75 11.00 1.28 1.28 1.25 1.25 0.80* 0.55* 12.00 1.25 1.251.20 1.20 0.75* 0.60* 12.50 1.20 1.20 1.20 1.20 0.78* 0.60* TESTDISCONTINUED FOR 10.25 HOURS 12.50 1.35 1.35 1.36 1.36 1.25 1.20 12.751.30 1.30 1.30 1.30 1.05 0.90 13.00 1.29 1.29 1.28 1.26 0.95 0.75 13.251.27 1.25 1.25 — 0.80 0.51 13.50 1.26 1.25 1.25 1.25 0.89 0.70 14.101.22 1.22 1.21 1.20 0.71 0.55 15.25 1.21 1.21 1.20 1.20 0.91 0.80 16.251.21 1.20 1.18 1.18 0.61 0.40 17.25 1.20 1.20 1.18 1.16 0.60 0.00 18.501.20 1.19 1.15 1.15 DISCONTINUED 19.50 1.19 1.16 1.10 1.10 DISCONTINUED20.50 1.13 1.11 1.10 1.10 0.99 0.81 22.25 1.10 1.10 1.04 1.05 0.49 0.0023.25 1.05 1.05 1.01 1.01 0.55 0.00 24.50 1.05 1.05 0.89 0.93 0.80 0.0025.75 1.02 1.02 0.49 0.90 DISCONTINUED TEST DISCONTINUED FOR 9 HOURS25.75 1.19 1.20 1.20 1.20 — — 26.75 1.01 1.01 0.99 0.99 — — 27.90 1.001.00 0.95 0.95 — — 28.50 0.99 0.99 0.85 0.86 — — TEST DISCONTINUED FOR21.5 HOURS 28.50 1.11 1.12 1.12 1.11 — — 29.50 0.99 0.99 0.90 0.89 — —32.25 0.94 0.95 0.39 0.95 — — TEST DISCONTINUED FOR 2 HOURS 32.25 0.980.98 0.99* 0.90 — — 34.40 0.81 0.91 0.91* 0.80 — — 35.75 {.65 {.65 {.65*{.65 — — TEST DISCONTINUED FOR 112.5 HOURS 35.75 1.09 1.09 1.12* 1.10 —— 40.35 {.65 {.65 {.65* {.65 — — TEST DISCONTINUED FOR 3.25 HOURS 40.350.98 0.99 0.95* 0.98 — — 41.35 0.60 0.52 0.45* 0.54 — — TESTDISCONTINUED FOR 13.75 HOURS 41.35 1.01 1.01 0.99* 0.97 — — 41.70 0.710.79 0.50* 0.70 — — TEST DISCONTINUED FOR 2 MINUTES 41.70 0.90 0.910.80* 0.81 — — *Replacement for Battery 2A

Table II sets forth the measured battery voltage drop of batteries 1A,1B, 2A, and 2B under load. The tests were commenced when the batteriespassed their operational half-life. As can be seen, the voltage drop ofa battery under load increased as the battery approached the end of itsuseful life. More indicative than the actual drop, is the amount of timeit takes to stablize the voltage under load. During the useful life ofthe battery, a voltage drop from the no-load voltage to the load voltageof the battery is an immediate single-step voltage drop. When thebatteries are beyond their useful life, the voltage drop is acontinuous, slow drop that can take some time stablize, sometimesexceeding 30 seconds. This is indicative that the batteries areexhausting their limited capacities.

TABLE II BATTERY VOLTAGE DROP UNDER LOAD (Incandescent Flashlight Bulbs)BATTERIES 1A & 1B BATTERIES 2A & 2B Test No Voltage No Voltage Time LoadUnder Voltage Load Under Voltage (Hrs) Voltage Load Drop Voltage LoadDrop 16.25 2.39 1.96 0.43 2.30 1.88 0.47 18.50 2.35 1.89 0.46 2.28 1.890.30 20.50 2.30 1.85 0.45 2.20 1.80 0.40 22.25 2.23 1.80 0.43 2.10 1.710.39 23.25 2.15 1.61 0.54 2.05 1.51 0.54 24.50 2.11 1.60 0.51 1.90 1.490.41 25.75 — — — 1.94 1.46 0.48 TEST DISCONTINUED FOR 9 HOURS 25.75 2.321.70 0.62 2.35 1.75 0.60 26.75 2.08 1.40 0.68 2.01 1.52 0.49 27.90 2.021.40 0.62 1.82 1.30 0.52 TEST DISCONTINUED FOR 21.5 HOURS 29.50 1.991.29 0.70 1.81 1.20 0.61 32.25 1.92 1.35 0.57 0.49* 0.10* 1.39* TESTDISCONTINUED FOR 112.5 HOURS 35.75 2.18 1.31 0.87 2.21* 1.10* 1.11* TESTDISCONTINUED FOR 3.25 HOURS 41.35 1.80 0.91 0.89 1.00* 0.48* 0.52**Replacement for Battery 2A

While the invention has been described with reference to specificembodiments, it will be recognized by those skilled in the art thatvariations are possible without departing from the spirit and scope ofthe invention, and that it is intended to cover all changes andmodifications of the invention disclosed herein for the purposes ofillustration which do not constitute departure from the spirit and scopeof the invention.

1. A battery package having a battery-strength indicator comprising: apackage frame; rechargeable batteries mounted on said package frame,each of said batteries having first and second terminals; abattery-strength indicator mounted on said package frame andelectrically connected to a first terminal of one of said batteries; anda battery switch comprising a resilient, nonconductive layer disposedover said package frame, a switch chamber disposed beneath saidresilient layer, a first conductor extending from said switch chamberand connected to said indicator, and a second conductor extending fromsaid switch chamber and connected to a second terminal of one of saidbatteries, said battery switch being biased in an electrically openposition, whereby upon pressing of the resilient layer over said switchchamber, the switch contacts will place said indicator in electricalcontact across the terminals of said batteries.
 2. The battery packageof claim 1 wherein said batteries are connected to said battery-strengthindicator and said battery switch in parallel.
 3. The battery package ofclaim 1 wherein said batteries are connected to said battery-strengthindicator and said battery switch in series.
 4. The battery package ofclaim 1 wherein said indicator comprises a LED array.
 5. The batterypackage of claim 4 wherein said batteries are dry cell batteriesconnected to said battery-strength indicator and said battery switch inparallel.
 6. The battery package of claim 4 wherein said batteries aredry cell batteries connected to said battery-strength indicator and saidbattery switch in series.